http://www.aana.com/aanajournalonline AANA Journal February 2019 Vol. 87, No. 1 41
Conclusion
Improving the outcome for patients undergoing prone
spine surgery has been limited with regard to ION. The
low incidence and lack of scientific evidence has made
recommendations difficult to make, with only 7 vari-
ables being identified by large studies as significantly and
independently associated with ION after spinal fusion:
obesity, male sex, Wilson frame use, longer anesthetic du-
ration, greater EBL, aging, and decreased percent colloid
administration.7,16 Because many of these variables cannot
be controlled, anesthesia providers have an obligation to
understand the current data regarding ION and to iden-
tify patients at increased risk of ION. An expert panel
survey, composed of mainly anesthesia professionals, by
the Anesthesia Patient Safety Foundation discovered that
86.6% of respondents believed that “most surgeons do
not recognize the risk of ION in the susceptible patient
population, whereas 52.2% felt the same was true for
anesthesia professionals”.^34 The use of a spine team con-
sisting of anesthesia providers who regularly do difficult
prone spine cases may be useful to help organizations
identify what defines a “complex” spine case and to create
guidelines for providers. Institutional identification of a
“complex” spine surgery would likely be determined by a
higher risk of hemodynamic instability, EBL, or anesthetic
duration. When possible, interventions such as vascular
embolization, tranexamic acid, large-bore intravenous
access, and staging procedures, may be useful to limit
the elevated risks for complications in “complex” spine
cases.35,36 Proper positioning to decrease venous conges-
tion such as patient head elevation above the level of the
heart, decreased abdominal compression, and avoidance
of Wilson frames, may also limit the risks of developing
ION.8,16 Theoretically, other interventions that decrease
venous congestion may also be helpful.
Due to the devastating effects of POVL and the un-
familiarity of most patients with this complication,
extensive discussion becomes mandatory when patients
have multiple risk factors for ION. During the informed
consent process, anesthesia professionals and surgeons
should include discussion of the remote risk of visual
impairment ranging from partial vision loss to complete
blindness in both eyes for patients considered to be at
risk of POVL from ION.
REFERENCES